1. Field of the Invention
The present invention relates in general to a data input and display device for use in a numerical control machine tool and more particularly, to such a data input and display device capable of enabling an operator to input shape data for a number of machining portions which are axially arranged on a cylindrical workpiece and of displaying on a display screen the shapes of the machining portions based upon the input shape data.
2. Discussion of the Prior Art
A known device of the aforementioned type is designed for a numerical control lathe as disclosed in U.S. Pat. No. 4,490,781 to H. Kishi et al. In this device, any portion on a workpiece cannot be displayed on a cathode ray tube (CRT) display unit unless data defining the shape of the portion is input. However, this does not raise any substantial problem because it is usual in lathe works to machine every portions on the workpiece.
To the contrary, in grinding works, it is usual to grind some portions on a workpiece, but not to grind some other portions on the workpiece, and no shape data is practically input except for those to be ground of the workpiece. Thus, in a known data input and display device for a model G62A-32X63 CNC full-automatic cylindrical grinder developed by the assignee of the present application, machining portions on a cylindrical workpiece are displayed on a CRT screen, with their shapes being discontinued if the workpiece has a portion not to be ground between two successive machining portions. This disadvantageously results in making it difficult for an operator to grasp the entire shape of the workpiece.
Further, the latter known device is provided with a function to display the workpiece shape along with a moving locus of a grinding wheel on the CRT screen for checking by the operator, of an interference of any non-machining workpiece portion with the grinding wheel. However, such interference checking is not reliable since the entire shape of the workpiece is not displayed on the CRT screen. Although the known device permits shape data for such a non-machining portion to be entered for displaying the entire shape of the workpiece, the inputting of the shape data for the non-machining portion is troublesome and therefore, is practically done.